Solar cells using silicon and dye-sensitized solar cells are known as photoelectric conversion devices. Among them, dye-sensitized solar cells have attracted attention since they are inexpensive and can obtain a high photoelectric conversion efficiency and various developments have been conducted toward further improvement in photoelectric conversion efficiency.
A dye-sensitized solar cell typically includes a working electrode having a semiconductor electrode provided on a transparent conductor, a counter electrode, a photosensitizing dye supported on the semiconductor electrode of the working electrode, an electrolytic solution disposed between the working electrode and the counter electrode, and a sealing portion provided between the working electrode and the counter electrode and around the electrolytic solution as main constituent elements, and the electrolytic solution is constituted, for example, by an electrolytic solution including an oxidation-reduction system (redox pair) such as, for example, I−/I3−.
In such dye-sensitized solar cell, electrons in the photosensitizing dye are excited by the incident visible light, and the electrons are injected from the photosensitizing dye that has thus been excited into a conduction band of the semiconductor electrode and flow out to the external circuit. The electrons that have returned from the external circuit reduce triiodide ions (I3−) into iodide ions (I−), the photosensitizing dye that has lost electrons and has been oxidized is re-reduced by the iodide ions (I−), and electric power is thus generated.
As such dye-sensitized solar cell, a photoelectric chemical cell in which volatilization of the volatile solvent contained in the electrolytic solution can be prevented by heating and melting Himilan (trade name, manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.), which is an ionomer, to seal the electrolytic solution has been generally suggested (see for example Patent Document 1).
Further, a photoelectric chemical cell has also been suggested in which volatilization of the volatile solvent contained in the electrolytic solution can be prevented by heating and melting an ethylene-vinyl alcohol copolymer to seal the electrolytic solution for the reason that the gas barrier ability of the copolymer is higher than that of Himilan (see for example Patent Document 2).
Further, in a dye-sensitized solar cell, a metal wiring is sometimes provided on the transparent conductor to take out a large current. When this metal wiring comes into contact with an electrolytic solution, corrosion occurs. For this reason, the metal wiring is covered with a wiring protection layer such as low-melting-point glass frit.
As such dye-sensitized solar cell, a dye-sensitized solar cell in which a metal wiring is disposed inside the sealing portion by constituting the sealing portion by the metal wiring and low-melting-point glass surrounding the metal wiring and photoelectric conversion efficiency is thus increased is also known (see for example Patent Document 3).    Patent Document 1: Japanese Patent Application Publication No. 2003-297446    Patent Document 2: Japanese Patent Application Publication No. 2007-149652    Patent Document 3: Japanese Patent Application Publication No. 2005-346971